Carbopol®-crospovidone interpolymer complex for pH-dependent desloratadine release

Hydrogen-bonded interpolymer complexes are prepared using special polymers interactions between relatively weak hydrogen bonds and other components when they are numerous with consecutive configurations. Drug molecules possessing hydrogen donor or acceptor groups or both intercalate into the complex and show different release patterns. While numerous studies have investigated polymer component behaviours in different media and the resulting drug release profiles, few have focused on the specific drug molecule state. Desloratadine was incorporated into a Carbopol(®)-polyvinylpyrrolidone (PVP) complex using a novel method and the dissolution and release profiles as well as the mediating interactions were investigated at different pH values. Our results indicate that the drug showed an immediate release pattern at an acidic pH, and therefore, the polymer complex likely had no dissolution retarding effect on the developed system. Furthermore, the protonated state of the drug enhanced its detachment from the polymer and subsequent dissolution in the medium. Contrastingly, higher pH values around the pKa of pyridine nitrogen strongly suppressed the dissolution in an exponential-like manner. This suggests that in addition to dissociating both linked polymers or dissolving one polymer group, active groups that facilitate hydrogen bonding can also play an important role in the release mechanism.